Just doing a fast search did not appear in that recommended linked answer, so I'll mention here. Consider that most of this cores have what is called a turbo mode: Not technically well explained but basically that mode can be triggered, when using one or less cores than the 4 ones,(running a single core app or other situation) so that it can run at higher clock rates. IE, the i7 870's each core rate might be 2.93MHZ, but in turbo mode, a single core app can run at 3.6 GHz. Not all the available cpus support this, but i7 cpus ones can, for example (some i5 do not have turbo, none of the i3 have it.).